/* =========================================================
   Mahad Khan — Portfolio
   Design tokens
   ========================================================= */
:root {
  /* base surfaces */
  --bg: #0a0c10;
  --bg-panel: #12151c;
  --bg-panel-alt: #171b24;
  --border: #232833;

  /* text */
  --text-primary: #edeff3;
  --text-secondary: #9aa3b2;
  --text-muted: #666e7d;

  /* contrasting accents (one per skill/theme category) */
  --accent-cyan: #3fd7c4;    /* languages */
  --accent-violet: #9d7bff;  /* ai / genai */
  --accent-amber: #ffb454;   /* ml / data */
  --accent-rose: #ff6b8b;    /* databases */
  --accent-sky: #5b9dff;     /* core cs */

  --font-display: "Space Grotesk", "Segoe UI", sans-serif;
  --font-body: "Inter", "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "Courier New", monospace;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;

  --container-w: 1120px;
}

/* =========================================================
   Reset
   ========================================================= */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; margin: 0; padding: 0; }
h1, h2, h3 { font-family: var(--font-display); margin: 0; }
p { margin: 0; }
button, input, textarea { font-family: inherit; }

.container {
  width: 100%;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 24px;
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}

:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 3px;
  border-radius: 4px;
}

/* =========================================================
   Header / Nav
   ========================================================= */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(10, 12, 16, 0.72);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.navbar {
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: 0.01em;
}
.logo-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-violet));
  color: #0a0c10;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 700;
}
.logo-text { font-size: 1.05rem; }

.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
}
.nav-link {
  font-size: 0.92rem;
  color: var(--text-secondary);
  transition: color 0.2s ease;
  position: relative;
}
.nav-link:hover { color: var(--text-primary); }
.nav-link::after {
  content: "";
  position: absolute;
  left: 0; bottom: -6px;
  width: 0; height: 2px;
  background: var(--accent-cyan);
  transition: width 0.2s ease;
}
.nav-link:hover::after { width: 100%; }

.nav-cta {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 8px 16px;
  border: 1px solid var(--accent-cyan);
  color: var(--accent-cyan);
  border-radius: 999px;
  transition: background 0.2s ease, color 0.2s ease;
}
.nav-cta:hover { background: var(--accent-cyan); color: #0a0c10; }

.nav-toggle-checkbox {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 6px;
}
.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  transition: transform 0.25s ease, opacity 0.25s ease;
}
.nav-toggle-checkbox:checked ~ .nav-toggle span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle-checkbox:checked ~ .nav-toggle span:nth-child(2) { opacity: 0; }
.nav-toggle-checkbox:checked ~ .nav-toggle span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* =========================================================
   Hero
   ========================================================= */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding-top: 80px;
}

.graph-bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  opacity: 0.5;
}
.graph-edges line {
  stroke: var(--text-secondary);
  stroke-width: 1;
  opacity: 0.25;
}
.graph-nodes circle {
  animation: pulse-node 4.5s ease-in-out infinite;
}
.node-cyan   { fill: var(--accent-cyan); }
.node-violet { fill: var(--accent-violet); }
.node-amber  { fill: var(--accent-amber); }
.node-rose   { fill: var(--accent-rose); }
.node-sky    { fill: var(--accent-sky); }

.graph-nodes circle:nth-child(2n) { animation-delay: 0.6s; }
.graph-nodes circle:nth-child(3n) { animation-delay: 1.3s; }
.graph-nodes circle:nth-child(4n) { animation-delay: 2.1s; }
.graph-nodes circle:nth-child(5n) { animation-delay: 2.8s; }

@keyframes pulse-node {
  0%, 100% { opacity: 0.55; r: 5; }
  50% { opacity: 1; r: 7; }
}

.hero-inner {
  position: relative;
  z-index: 1;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--accent-cyan);
  background: rgba(63, 215, 196, 0.08);
  border: 1px solid rgba(63, 215, 196, 0.3);
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 24px;
}
.eyebrow-dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--accent-cyan);
  box-shadow: 0 0 0 4px rgba(63, 215, 196, 0.18);
}

.hero-title {
  font-size: clamp(2.6rem, 7vw, 5rem);
  font-weight: 700;
  line-height: 1.02;
  background: linear-gradient(120deg, #ffffff 30%, var(--accent-cyan) 65%, var(--accent-violet) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  max-width: 14ch;
}

.hero-role {
  font-family: var(--font-mono);
  font-size: clamp(1rem, 2.4vw, 1.3rem);
  color: var(--accent-amber);
  margin-top: 14px;
}

.hero-tagline {
  margin-top: 20px;
  max-width: 560px;
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-top: 36px;
}

.btn {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  padding: 13px 26px;
  border-radius: 999px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, background 0.2s ease, border-color 0.2s ease, color 0.2s ease;
  display: inline-block;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary {
  background: var(--accent-cyan);
  color: #0a0c10;
}
.btn-primary:hover { background: #58e4d2; }
.btn-outline {
  border-color: var(--border);
  color: var(--text-primary);
}
.btn-outline:hover { border-color: var(--accent-cyan); color: var(--accent-cyan); }

.hero-stats {
  display: flex;
  gap: 40px;
  margin: 56px 0 0;
  padding-top: 28px;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
  max-width: 560px;
}
.stat dt {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  text-transform: uppercase;
}
.stat dd {
  margin: 6px 0 0;
  font-weight: 600;
  font-size: 0.98rem;
}

/* =========================================================
   Section shells
   ========================================================= */
.section {
  padding: 110px 0;
}
.section-alt { background: var(--bg-panel); }

.section-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  color: var(--accent-violet);
  margin-bottom: 14px;
}
.section-title {
  font-size: clamp(1.7rem, 3.6vw, 2.4rem);
  font-weight: 600;
  max-width: 20ch;
  margin-bottom: 20px;
}

/* =========================================================
   About
   ========================================================= */
.about-grid {
  display: flex;
  gap: 64px;
  align-items: center;
}
.about-visual { flex: 0 0 300px; display: flex; justify-content: center; }
.about-content { flex: 1; min-width: 0; }

.about-text {
  color: var(--text-secondary);
  margin-bottom: 18px;
  max-width: 60ch;
}

.about-facts {
  margin-top: 28px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.about-facts li {
  display: flex;
  gap: 16px;
  font-size: 0.92rem;
  padding: 12px 0;
  border-top: 1px solid var(--border);
}
.fact-label {
  flex: 0 0 120px;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding-top: 2px;
}

.node-frame {
  position: relative;
  width: 300px;
  height: 300px;
}
.node-frame-ring {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 1px dashed var(--border);
}
.node-frame-initials {
  position: absolute;
  inset: 40px;
  border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, #1a1f2b, #0d0f14 70%);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 3.2rem;
  font-weight: 700;
  color: var(--accent-cyan);
}
.node-edges {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}
.node-edges line {
  stroke: var(--border);
  stroke-width: 1;
}
.node {
  position: absolute;
  width: 14px; height: 14px;
  border-radius: 50%;
  box-shadow: 0 0 16px currentColor;
}
.n1 { top: 15%; left: 8%;  background: var(--accent-cyan);   color: var(--accent-cyan); }
.n2 { top: 10%; right: 8%; background: var(--accent-violet); color: var(--accent-violet); }
.n3 { bottom: 12%; left: 4%; background: var(--accent-amber); color: var(--accent-amber); }
.n4 { bottom: 14%; right: 6%; background: var(--accent-rose); color: var(--accent-rose); }

/* =========================================================
   Skills
   ========================================================= */
.skills-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}
.skill-card {
  flex: 1 1 300px;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-top: 3px solid var(--card-accent, var(--accent-cyan));
  border-radius: var(--radius-md);
  padding: 26px;
}
.section-alt .skill-card { background: var(--bg-panel-alt); }

.skill-card[data-accent="languages"] { --card-accent: var(--accent-cyan); }
.skill-card[data-accent="ai"]        { --card-accent: var(--accent-violet); }
.skill-card[data-accent="ml"]        { --card-accent: var(--accent-amber); }
.skill-card[data-accent="db"]        { --card-accent: var(--accent-rose); }
.skill-card[data-accent="cs"]        { --card-accent: var(--accent-sky); }

.skill-card-title {
  font-size: 1.05rem;
  margin-bottom: 16px;
  color: var(--card-accent, var(--text-primary));
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.chip {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  white-space: nowrap;
}
.chip em { font-style: normal; color: var(--text-muted); }

/* =========================================================
   Projects
   ========================================================= */
.projects-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
}
.project-card {
  flex: 1 1 460px;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 30px;
  position: relative;
  overflow: hidden;
}
.project-card::before {
  content: "";
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 3px;
  background: var(--card-accent, var(--accent-cyan));
}
.project-card[data-accent="ml"] { --card-accent: var(--accent-amber); }
.project-card[data-accent="db"] { --card-accent: var(--accent-rose); }

.project-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 14px;
}
.project-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--card-accent);
}
.project-year {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}
.project-title {
  font-size: 1.35rem;
  margin-bottom: 6px;
}
.project-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 18px;
}
.project-points {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 22px;
}
.project-points li {
  position: relative;
  padding-left: 20px;
  font-size: 0.94rem;
  color: var(--text-secondary);
}
.project-points li::before {
  content: "";
  position: absolute;
  left: 0; top: 8px;
  width: 8px; height: 8px;
  border-radius: 2px;
  background: var(--card-accent);
}

/* =========================================================
   Contact
   ========================================================= */
.contact-grid {
  display: flex;
  gap: 60px;
  align-items: flex-start;
}
.contact-intro { flex: 1 1 380px; }
.contact-form { flex: 1 1 380px; }

.contact-links {
  margin-top: 32px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.contact-links a {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 4px;
  border-top: 1px solid var(--border);
  transition: transform 0.2s ease;
}
.contact-links li:last-child a { border-bottom: 1px solid var(--border); }
.contact-links a:hover { transform: translateX(6px); color: var(--accent-cyan); }

.contact-icon {
  flex: 0 0 38px;
  height: 38px;
  border-radius: 10px;
  background: var(--bg-panel-alt);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
}
.contact-icon svg { width: 18px; height: 18px; }

.contact-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}
.contact-value { display: block; font-size: 0.95rem; margin-top: 2px; }

.contact-form {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
}
.form-row {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 20px;
}
.form-row label {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}
.form-row input,
.form-row textarea {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  color: var(--text-primary);
  font-size: 0.95rem;
  resize: vertical;
  transition: border-color 0.2s ease;
}
.form-row input:focus,
.form-row textarea:focus {
  border-color: var(--accent-cyan);
  outline: none;
}
.form-submit { width: 100%; text-align: center; border: none; }
.form-note {
  margin-top: 14px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* =========================================================
   Footer
   ========================================================= */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.back-to-top { color: var(--accent-cyan); font-family: var(--font-mono); font-size: 0.8rem; }

/* =========================================================
   Responsive
   ========================================================= */
@media (max-width: 860px) {
  .about-grid, .contact-grid { flex-direction: column; }
  .about-visual { order: -1; }
  .node-frame { width: 220px; height: 220px; }
}

@media (max-width: 720px) {
  .nav-toggle { display: flex; }
  .nav-menu {
    position: absolute;
    top: 100%; left: 0; right: 0;
    background: var(--bg-panel);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    align-items: flex-start;
    padding: 20px 24px 28px;
    gap: 18px;
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.2s ease, opacity 0.2s ease;
  }
  .nav-toggle-checkbox:checked ~ .nav-menu {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav-cta { align-self: flex-start; }

  .hero { padding-top: 96px; text-align: left; }
  .hero-stats { gap: 28px; }
  .section { padding: 76px 0; }
}

@media (max-width: 480px) {
  .hero-actions { flex-direction: column; }
  .btn { text-align: center; }
  .contact-form { padding: 22px; }
}